Toric spectacle-glass.



.MQVON ROI-IR. TOEIC SPECTACLE GLASS. APPL'IQATION FILED AUG; 25, 191`0.

Patented A111218, 1911 FLW F3 v F5 F7 FF FWF M. VON EUHR.' TOEICSPECTACLE GLASS.

APPLICATION FILED AUG. 25, 1910.

Patented Apr. 1 8, 1911.

2 SHEETS-SHEET Z.

I F14L F16 F13 F1920 F1922 FWF MORITZ VON ROER, F JENA, GERMANY,ASSIGNOR TO-THE ATENT 0 FICE.

FIRM 0F CARL ZEISS, 0F

JENA, GERMANY. Y

TORIC SPECTACLE-GLAS`S Y Specification of Letters Patent.

Application led A ugust 25, 1910. Serial No.

Patenten apr. 1s, 1911. 578,863.

I' which are intended, to. compensat the astigmatic. defectot an eye.but opposite astigmatism, namely tov toric glasses, both sphere-torioand bitoric. In the sphero-toric glasses the cal surface lies in. the.equatorial plane of the torio surface. The. axis of the -g-lass lies inthis equatorial plane., contains the above mentioned center andintersect-s the axis of the toricsurface.- `With, the bi-toric glassestwo cases are to be distinguished. The axes of the tWot-oric snrfacescan lie parallel to each other. But they can also cross one y another atrightangles. In the case of the effect of its parallel axes theequatorial plane is common to both surfacesand the` axis of the glasslies in this plane and intersects the axes of both surfaces. In the caseof the axes which cross one anothenat-,right angles, the two equatorialplanes are perpendicular to each other. of the glass. All torio glassesbelong to the loi-symmetrical ones, z'. e. to those with two planes ofsymmetry, which intersect at right angles the axis of the glass. Withthe sp'erotoric glasses and the bi-toric ones with parallel axes, theone plane of symmet-ry vis formed by the equatorial plane of the toriosurface or surfacesrespectively, 'the other by that meridional plane ofthe toricy surface or surfaces respectively which contains the axis ofthe glass. With the bitoric glasses.` in which the axes of the toriosurfaces cross one another at right angles, thev two equatorial planesof these surfaces represent the planes of symmetry.

he object of the-invention is to bring the deficient optical effect ofthe zones of the torio glass as near as possible to the correct vertexplace. From this correct eiect, according to the investigations whichledt'o the invention, the average eii'e'ctof a center o tE the` spherijTheir line of intersection is the axis l zone, in each torio, spectacleglass, deviates l more than the ineanfof the two effects, which iappertain totwo places of the zone, chosen as will be now described-For. this choice, the f ttur places come into, consideration, in which9. i As the diametrically OppOSed places` are j equal 1n their` effect,the above proposition l concerns leither one` of thejtwoplaces, whichone, and1 either one of the two places, which are intersected bytheAplanes of symmetry'intersect 4 the zone.44

yother plane of symmetry. Further, the averageeiect of a zone -is somuch the better, it approximates so much nearer to the'efect of thevertex place, the less the mean of the two effects of two placesin thiszone, chosen as stated. deviates from the ei'ect of the vertex places,this mean according to the first proposition, always 'better than thataverage effect. l In order to ascertain the eitect of a place,

which belongs to'a plane of symmetry, the

place is to be considered as one through which a principal raypasseswlnch travels in the plane of symmetry anu intersects the l axisabout 3 cm. behind the eye side vertex l of the spectacle glass, i. c..wherel in theprac I' tical use of the spectacle glass the point of'rotation ot the eye is situated. In the verl tex place of the glass,which belongs to both planes of symmetry, the axis represents the iprincipal ra-y. For any place whatever 1n the toric spectacle glass theoptiea-lefect res'ults from the two different powers, which,

are effective in the two principal planes longing to the principal ray.The principal' I planes are perpendicular to each other, as l iswell-known- When the place under-conl sideration lies in a plane ofsymmetry, this I plane represents the one principal pla-ne. For the'vertex place both planes of symmetry become principal planes.` Iffor a,

in one ofthe l place outside the vertex, lyin' e two powers two planesot symmetry, of t l the one, which is e'ective in symmetry, were just asgreat aS the pmt-Q15 which is eti'ective inthe same plane at the vertexplace, and it further for t e place lun- I der consideration theother.paowetg 4which.,

according to thev above, is'etfective in afplan" this plane of*v Ilmperpendicular to this same plane, were also similar to the power, whichbelongs .to the vert-ex place in the other 'plane of symmetry, thenthe'eifect of the place under consideration wouldcompletely equal theeifect of the.

i vertex. Should the same also hold goodfor a place in the same zone intheother plane of symmetry, the above mentioned mean would not deviateat all from the elfect of the vertex place, and so the optimum for theaverage effect'of the zone would be attained.

A toric spectacleglass of the just described optical characteristicscannot be realized. According to the invention a toric' glass approachesnearest to this ideal, when the effects of two places in4 a zone, whichare intersected respectively byl theI one and the other plane ofsymmetry, are approximately. .equalto eachother. Toric glassesfulfilling this requirement are not known.. The examination of existingtoric glasses has always shown instead of approximate similarity aconsiderable divergence Abetweenfthe two effects here considered. ,Eachof the two' nearly similar effects already represents approximately themean, of which it was ascertained above, that 1t approximates moreclosely to the effect of the vertex place than average' eii'ect of thezone approximates more 'closely to 'the above mentioned optimum than canbe-the case, when the effects of the two places in the zone differconsiderably. Exact similarity between the effects of two places in azone, which are intersected re- Ispect-ivelyby thev one andthe otherplane of symmetry, exists then, when the two powers of the one placeequal the two powers of the other.' In this case vthe difference betweenthe-twopowers, e. the measure of the astiginat-ismf (they astigmaticdifference) is the same forboth places. According to the in- -ventionthe similarity ofthe astigmatic differences, withl the'exception ofparticularly powerful collective glasses, can b'e attained accuratelyat-'least'for'one zone, c. g. the

marginal zone'. 4The agreement of either power of the one place with thecorrespondingpower ofi-the other place, -which would still be requisiteiii vorder to make'the effects of the twoplaces exactly similar, cannotbe realized. But even for the marginal zone the diii'crence between thecorresponding 'powers in both cases need not by a long way amount to thefifth part of the astigmatic `difference at the vertex place.

The difference in the sharpness of the image when .using both marginal`places, which corresponds to a. difference vof the powers of the otherplace correspond to `one another, when the one powei acts in the planeof symmetry, which intersects its place, the other in the plane. whichis perpendicular to the other plane of symmetry. l A

Inn the annexed drawing: Figure'l is a sec tion along one plane ofsymmetry of a.

.sphe'ro-toric dispersive spectacle glass constructed according to theinvention. Fig. 2 is a. section alongthe other plane of sym-' metry.Fig. Sis a section along one plane of symmetry of a: second form ofsphero-toric dispersive glass. Fig. 4 is a sectionalong the other planeof symmetry. Fig. 5' is a section -along 'one plane of symmetry of athird form of sphero-toric dispersive glass.

Fig. 6 is a section along theother plane of symmetry. Fig. 7 is asection along one Iplane 'of symmetry of a fourth form ot' sphere-toricdispersive glass. Fig. 8 is a sect-ion along the other plane ofsymmetry. Fig. 9 is a section along one plane of symmetry of a bi-toricdispersive glass, the toric surfaces of which have parallel axes. Fig.10 is a section along the other plane of symmetry.l Fig. 11. is asection along one plane of symmetry of a bi-toric dispersive glass, thetoric surfaces of which have axes which cross eachother at rightangles.Fig. 12 is a section along the other plane of symmetry.

Fig. 13' is fa section -along one plane of symmeti'yof a sphero-toriccollective'glass. Fig.

, 14 is a section along the other plane of symmetry. Fig. 15 is asection along one plane of symmetry of a second form of spherox toriccollectiveV glass. Fig. 16 is a section along the other plane ofsymmetry. Fig. `17' lis a section along one plane of-symmetry of a'third form of sphero-toric collective glass. Fig. 18 is a sectionaloiigthe other plane of symmetry. Fig`f19 is a section along one planeof symmetry of a fourth form of spliero-toric collective glass. Fig. 2Ois av section along the other'plane of symmetry. Fig. 21 is.asection-al'ong one planel of sym* metry ofla bi-toric collective glass,the toric surfaces of whichhave Iparallel axes. Fig. 22is a sectionalong the otherplane of symmetry. Fig. 23 is a sectionA along one planeof symmetry of a' bi-toric collective glass, the toric surfaces of whichhave'axes which cross eachother at right angles. Fig. 24 is a sectionalong the other plane of symmetry. Each glass is assumed to be of acircular form, in order to indicate,`that with a hori.- @rental axis thepair of planes of symmetry may be located as desired. l

In the following tables there are given for each example first of alltheV two powers F55 pointoftheglass in each case should hay@ l A- 0.00

eee-.645 3 prescribed, and realized at the vertex place, served asthe'starting-poi'nt. But on account viz. M for the one plane ofsymmetry, the of the very small distance of the same from M-plane,corresponding'to the upper ligure, the hinder vertex the two refractionValues 'and A for the other plane of symmetry, 4the .do not differpractically. 5 A-plane, corresponding to the lower figure. L DISPERSWEGMSSES- 70 Then follow the radii r and the vertex thickv ness (Z. Aradius of the frontY surface has Flgs'land below it the .index l, aradius of the hinder ...FHMmmMgfffgngpggn d=0 5mm surface has in thesame place the index 2. 1510;; gggfdm Q?Iggdptr Bggdpm If the surface isa torio one, its two radii are M 4.00 :i 3.00 j: 3.20 :j 75

also marked by an upper index, by m, when ML' jgg i the radius is thatof the M-plane, by a, when Mhj *i2 jj f ggg ff the radius is the oneinthe A-plane. By the Mm M 0.' 00 011s j: 013e i 0. 09rrr-A; suitablecoordination of M and A to the one ALM: No 17 037 :(loglM-A. and theother plane of symmetry, the index Flgs'flmd'l S0 m Signies for eachtorio SuljfaGe-except* rmi=67.6mm. d=0.5mm. ing the hinder surface ofthe bi-toric glasses, w' 0. 00 20.70 30.0006 t the axes of which crosseach other at right I :jggdflr dll. 12.- angles-at the same time themeridional Mmjgg fi If .i radius, the index a the equatorial radius..fx1- 8.00 j: 7:07 fl' jj 85 Eer the said hinder surface, on the otherLQ. jgg -i i 0j32 0pg'(1\; A) "fhand, m indicates the equatorial radiusand -A.A'= @loo 11 132 mmm-A) a the meridional radius. Each tabilec0111- Fiyemld. tins also for a middle Zone an or tie M 40pm A 80pmniarginal zone, which areboth characterized "Fl-1&0 bompmgrg 2=4,'%0-?=j d07mm' 90 by the angles of inclination e0 of the prin- :ggg dpfr.:grgdgtn :gz dgn. cipal rayon the eye side, the point of inter- Mln-; ggi; ggg :j Lg 07 I: section of the principal rays having a disl.: :sjoo n7 87 i 7164 H tance of 25 nini. from the hinder vertex of fgj f. :am M.A) u16 giass, the foiiowing (im. Firstly, nie .im-M 0.00 0.17 l 0.440.11 lM- A-i 95- power Mm of that place in the zone which 1s Figs. 70nds. intersected by the M-plane7 being efeetive M super. A 40a in thissame plane, the power Am of the saine T0120 fl fmFwgg- T'Ff 033m(F0-7mmplace, being eective in the principal. plane IIE :ggg dan. :5.den. perpendicular to the M plane, and the astig- MLM; 41'00 i 359g l:3191 I: 100 matic difference Mm-Am of the place under ffi :figg ff :Zj:ggg consideration. Secondly, the power M of ar ggg j; 152g? fr g Uff =012 (M A tllepliflC ln the ZHG, ll'ltelSeCted the A- Ain-An;- QSO() l 0:23 H' 0:46 =912\ M' A3 plane, being effective in the principal plane Fgs9ad.,0 105 4o perpendicular to that plane,v the power Aa M: mmh A= Sdptnof the same place, being effect-ive in the A- @FB2-4mm. e:=1l 2-d111[1)17rfznz'9mmI m=45262mm plane, and the astigmatic differenceMEL-Aa. 1li/ 0. 00o 20.70' '30.00 Thirdly, the differences m--Mal anddll?" 22:3? dlt"- :dllr' Anl- Aa or' the corresponding powers of bot-hMm-i g ff gl-gg jf g ff no places. The values for the Vertex place M8.00 i 7.90 i i (fl/.,wzoo) are in each case added, I. jg i j :A gj uggf Ain-M 0.00 l N lf=ge=Mf=ga and AT UQ-:Ajego Figs' 11 and12 v airainre )resenting the two iowers M and A M 4 apn. A= a dpnr. pescribeld fortlie glass. lFinally there is T"=92'4 mm' rarushys'gnlm' T'`4l'3mm` 115given, what fractional part ,the differences i Q -ghn. dptr gdptr' m7.90 and ii'xl'maxnAiihnax Mln-2 of corresponding powers of the -placesunder m`: *ggg 2f *figg ff jg If 120 consideration in the marginal zoneconsti- M-Mm j; f.' 83g? 1.23112 $12;

tute of the prescribed astiginatic difference A `A= M A. The refractive.index 0U is for al1 1I. COLLECTIVE GLASSES l2 examples 1.52.' Each] powe1relates 20' Figs. 1300014. (that 'ointoftherinci )a ray e onging 0 M+4prr. A +1 depts it 4onlibe eye si" 1V.whichl.likethehinder ver-"=ff,=2 nf'(fb0"f=3-l2l9e ffig'off flgmm" 125 tex 'ofg'the 0l hasA a"'distance of `25 nim. M lggdnfr. dgtrf. 13.554132@ ronrthepointointersectionfoffthe princi- .wr- Am; 2100 I: s100 f: ggg if.palxnrafy'sf cixcco rdiiig to'the/ strict sense of l gli I'. :I gj :i

the` terni power` .the hinder principal I g2g?) H- j: gg :i :82E g; :laol Figs. 15 and 16.

7 mm. (im-1.9 mm. .00

rmi=48.0 mm. #1:6515 mm.

M2745 mm. d:1.9n11n. 4

Mm:- +4. 00 dptr. +3. 90 dptr. +3. 71 dptr.

Am: +1.02 +0. 82 +0. 57 MB1-Am: 2.98 3.08 3.14

Ae: +1. 02 +0.08 +0.91 MlfAe: 2.98 3. 3.15

Mln-Mn: 0.00 0.14 0.35 :0.12 (M-A) AIL-M: 0.00 0.10 0.34 :0.12 (M-A)Figs. 1 and M: +4 dptr. A: +1 dptr. 1ml:50.8 mm. 1:96.00 1mq:81.7 mm.'1z:116.8 mm.

.9 m w: 0.007 23.93 35. 00 Mm: +4. 00 dptr. +3. 04 dptr +3. 80 dptr Am:+1.00 0.86 0.05 Mln-Am: 3.00 3.08 3.12 M +4.00 +4.08 +4. 1G A +1.00+1.04 +1.06 Mln-A 3.00 3.04 3.10

Mie-MH: 0.00 0.14 0.36 =0.12 (BI-+A) Am-A 0.00 0.18 0.38 =0.13 (MA)Figs. 23 and 2l..

' M: .+4 dptr. A: +1 dptr. rw1=40.0 mm. m=67-0 mm. Ym2:66.4 mm.a'f-2:7G.0 mm.

(1:1.9 mm. w': 0. 00 23.93 35.00

f Mm: +4.00 dptr. +3. i8 dptr. +3. 49 dptr.

Am: +1.00 +0. 75 +0.40 Mln-Am: 3.00 3.03 3.03 Me: +4.00 +3.98 +3. 95 A5:+1.00 +0.96 +0. 00 M-A: 3.00 3.02 3.05 Mln-Me: 0.00 0.20 0.40 :0.15:1f-A) 0.00- 0.21 0.44 =0. 15 M-A) I claim: 1. Toric' s ectacle, glass,in which the powers eiectlve inthe lacespf the niarginal zone, throughVWhich pass'two prncipal rays trayeling respectivelyvin the one andtheother plane of'symmetry and intersecting at the same inclination to theaxis in `the same axis point, about.3 cm. behind the vertex on the eyeside, have such values, that the difference between that one of thetwo'powers of one of the tito places, which is etfectivein the plane of'symmetry intersecting this place, and the power of the other place,beingeiective in the principal plane perpendicular to that plane ofsymmetry, which intersects this other place, amounts to the fifth partat the most of the astigmati difference at the vertex.

2. Toric spectacle glass, in which the powers eHective in the places of,the marginal zone, through which pass ttvoprn` cipal rays travelingrespectively'in the one and the other plane `ot Symmetry andintellsecting at the saine' inclination to the axis in the same axispoint7 about 3 cm'. behindl the vertex on the eye side, have suchvalues, that the difference between that one of the two-powers of one ofthe two places, which is effective in the plane ofsynnnetry intersectingthis place, `and the power of the other place, being effective in theprincipal plane perpendicular tcl that yplane of sym-` metry. `whichintersects this other' place, amounts to the fifth part at the most ot'the astiglnatic difference at the vertex. the astigmatic difference atone place and that at the other place being the same.

MORITZ VON ROHR. lVit'nesses PAUL KRGER, ALFRED MECKEDANZ.

Copies o1 this patent may be obtained forve cents each, by addressingthe Commissioner of Patents.

Washington, D. C.

